The inventive concept relates generally to a nonvolatile memory device using a variable resistive element.
Examples of nonvolatile memory devices that use resistance material include phase change random access memory (PRAM), resistive random access memory (RRAM), magnetic RAM (MRAM), and the like. While dynamic random access memory (DRAM) or flash memory stores data using an electric charge, a nonvolatile memory device that uses resistance material stores data using a change in resistance of a variable resistive material (e.g., RRAM), a change in state of a phase change material (e.g., PRAM), such as a chalcogenide alloy, and a change in resistance of a magnetic tunnel junction (MTJ) thin film due to a magnetization state of a ferromagnetic substance (e.g., MRAM).
The following description uses a phase change memory cell as an example. A state of the phase change material is changed to a crystalline state or an amorphous state while being cooled down after a heating process. Since the phase change material in the crystalline state has low resistance and the phase change material in the amorphous state has high resistance, the crystalline state may be defined as set data or 0 data, and the amorphous state may be defined as reset data or 1 data.